Slag resistance refers to the ability of the refractory to resist chemical erosion, and the slag resistance is very heavy when the initial layer of the kiln skin is formed and when the material is viscous or local high temperature causes the kiln skin to fall off to.

The porosity and thermal conductivity play an important role in forming the initial layer of the kiln skin, and refractory materials with high porosity and thermal conductivity can help the timely repair of the kiln skin when the kiln skin is partially shed. But at the same time, it may show a great destructive effect, so that the thin layer of refractory brick peel off.

In the process of production, the physical and chemical changes of refractory bricks generally do not reach the equilibrium state at the firing temperature. There are also insufficiently fired refractory bricks, so when subjected to high temperature action in rotary kiln, most refractory bricks undergo irreversible refiring shrinkage due to the production of their own liquid phase and the filling of pores. Therefore, high temperature volume stability must be considered in the selection of fired refractory bricks. The layered stripping of hot surface is the main form of damage of kiln lining after thermal shock. If the local denser peeling occurs at the same time, the service life of the firebrick will be greatly shortened. When coal is used as fuel, the volatiles and ash of coal play a decisive role and directly affect the flame shape. Pulverized coal with higher volatile content and lower ash content can shorten the black flame head and form low temperature long flame calcination. It is generally favorable to protect the kiln lining, but the volatile content is too high, the fire is too fast, the kiln clinker temperature is as high as 260°C or more, the secondary air temperature is more than 900 °C, and it is easy to burn the nozzle, so that it is deformed or burned to appear a notch, resulting in a chaotic flame shape, which damages the kiln lining before it is replaced. The volatile content of coal is too low, the ash content is too high (more than 28%), and the incomplete combustion of a large number of pulverized coal will settle in the material and burn and release a lot of heat, which will also damage the kiln skin.

The fuel nozzle structure is often not paid enough attention in the production, the nozzle shape and outlet size are mainly affected, the mixing degree of pulverized coal in the same wind and the ejection speed, sometimes in order to strengthen the mixing of air coal can also be installed in the nozzle wing, but pay attention to the swirling wind rotation amplitude is too large to damage the kiln skin.

When the aluminum ratio is too high and the liquid phase viscosity is large, a large number of kiln skins collapse, which is not easy to control in operation, and is unfavorable to the protection of the empty lining. The aluminum ratio in production practice is generally controlled at 1.3? 1.6: When high saturation ratio, high brick ratio and low liquid phase blending is adopted, it is easy to cause erosion of viscous material and abrasion of kiln skin to make the kiln thin and seriously damage the kiln lining. In production practice, when Si 2.5 is used, the saturation ratio should not exceed 0.92; when IDn 2.8 is used, the saturation ratio should not exceed 0.90. The fluctuation of raw feed amount is more harmful to the kiln lining. When there is too much incoming material in the kiln, it is necessary to turn off the exhaust air volume of the small kiln tail and increase the amount of pulverized coal for forced firing, so that the heat load of the firing belt increases rapidly, and the kiln lining is seriously damaged. When there is too little incoming material in the kiln, the flame of pulverized coal obviously falls down, and the kiln skin in the area will fall off and become thinner at high temperature, and it will rush to the thinner material layer. If the air volume and coal consumption are not adjusted in time, the kiln skin and refractory brick are easily burned. In addition, the fluctuation of raw feed amount will cause the internal thermal system to be unstable, the temperature is too high, and the kiln skin will fall off or be damaged.

Therefore, when the clinker temperature out of the kiln is above 1260° and the secondary air temperature exceeds 900C, it is easy to burn the nozzle, causing it to deform or burn a notch, resulting in a chaotic flame shape, which makes the kiln lining easily damaged. The clinker rate is generally controlled at KH0.91±0.01, the silicon rate is 2.6±0.1, and the aluminum rate is controlled between 1.3-1.6. It is very beneficial to protect the service life of firebrick and improve the strength of clinker.